Consumer demand is a driving force in the garment industry. The popularity of denim garments having a faded and worn look have caused many manufacturers of such garments to seek ways of finishing or processing assembled denim garments to provide them with the faded look and soft feel so desirable to the consumer. This has led to the development of equipment and processes for bleaching and abrading assembled jeans to achieve the desired faded and soft look and feel.
In one treatment, called "pre-washing", the garments are simply laundered before sale to remove fabric sizing. This gives the garment a softer appearance and feel, but does not appreciably fade the color of the garment.
Fading (and softening), through mechanical abrasion and/or chemical processing, is typically accomplished in "stone-washing." In this process, the garments are washed in a washing machine along with a suitable abrasive medium such as pumice stones or the like. A dilute solution of bleach is also typically used, either as an impregnate in the stones or as a separate solution added during the wash cycle. As the garments are processed, the stones abrade the surface of the garments, and the bleach fades the color. Control of the concentration of the bleach and the time span of the process is very important since this process can damage the machines and garments. Furthermore, this process produces pumice debris which accumulates in garment pockets, clogs machines and pollutes the environment. Once completed, this process requires additional manufacturing steps to separate the garments from the stones and stone debris.
These and similar methods are typically used to treat a group of garments more or less uniformly at the same time. They change the denim garments from stiff and uniformly colored to worn, faded, and soft. The treated garments are typically more comfortable to wear. However, because these processes involve the treatment of bulk lots of garments, they cannot duplicate the effects of actual wear which produce local variations in the amount of fading, with the heavier fading (and areas of wear) on the front of the thighs, the crotch, and the seat, and along sewn seams and pocket edges.
Hand treatment of jeans has been resorted to in order to duplicate the localized effects of actual wear, since more sophisticated techniques have not been available. Workers wielding wire brushes or sanding wheels or paint sprayers with bleach or sand can fade, abrade or completely wear away specific areas on jeans, producing a faded effect on local areas such as the front thighs or seat.
For example, European patent EP 0 377 417 A1 to Cingolani, discloses a method of locally decolorizing dyed fabric with a jet of hot pressurized water, which avoids the use of chemicals. The garment can be placed on an air-inflatable mannequin, for stretching. When air is blown into the garment it pushes against the inside of the garment and expands it. However, because the water jet must penetrate the fibers in order to fade the cloth, the water pressure must be higher than the mannequin inflation pressure, to obtain the necessary penetration of the fabric by the hot water jet.
In U.S. Pat. No. 4,845,790 to Brasington, a fixture is used to hold jeans for inflation and bleach spraying with a hand-held paint sprayer. The jeans are pre-washed and stone-washed, spun dry, and then while still damp are mounted on a fixture which freely swivels over a large air duct which blows air through the jeans' waist into the garment, inflating it for treatment. The garment is treated on one side, then swivelled around by hand for treatment of the other side. To prevent the jeans from sliding off, the lower perimeter of the swivel sleeve has a circumferential protruding lip over which the jeans waist band rides. A snap clip is used to tuck up extra waist band material of the jeans on one side. (The jeans are thus slightly off-center when mounted on the swivel sleeve.) Two more clips are required to close off either leg sufficiently to stop up the air flow and inflate the garment. Because the garments being treated are porous, the air being pumped into the garment to inflate it is also being forced out through the garment pores. This acts as a countercurrent against the bleach being sprayed onto the garment, and tends to prevent penetration of the bleach into the fabric. Furthermore, like the European Patent to Cingolani, this process is not adaptable to mass-production, depends for the success of its results on the skill of the individual who wields the spray mechanism, and thus is not capable of reproducing with precision substantially identical effects from one garment to the next.
Therefore, the need exists for automated equipment and processes for producing specific, desired local finishes, such as variations in the amount of fading of an assembled garment to simulate the effects of actual wear, which are capable of being substantially identically reproduced from garment to garment on large numbers of assembled garments.